1. Field of the Invention
This invention concerns storage of products such as petroleum products. More particularly, it is concerned with the draining of water from storage tanks of hydrocarbons such as aviation jet fuel.
1. Description of the Prior Art
In connection with storage tanks for petroleum products such as aviation fuels and the like, there has always been a problem with the removal of water which tends to gather inside the tank from various sources. Of course, such water settles to the bottom. Under present conditions it is of much increased importance to be able to remove such water from storage tanks without any loss of the hydrocarbons product from the tank. This is of course true for at least two reasons, one being the value of petroleum products in todays markets and the other being the strictures against pollution such as by reason of having petroleum products mixed with surface drainage or the like.
Heretofore, there have been various types of apparatus that are available which make use of drawing tank bottoms into a small vessel where further separation of oil and water takes place prior to drawing off the water layer for disposal. The hydrocarbon liquid is then pumped back into the main storage tank from the separate vessel. With such arrangement the liquid must be returned against the full head of the hydrocarbon in the storage tank so that a pump using electric or pneumatic power is required. Furthermore, such systems require additional equipment which adds considerably to the expense and complications.
There has been suggested in the past, a separator structure as described in U.S. Pat. No. 2,036,730 to H. A. Thompson issued Apr. 7, 1936. However, that structure is quite complex and includes various chambers and float actuated elements for creating the desired separation of liquids in order to carry out the desired removal of a heavier liquid such as water.
In addition, there are various float actuated valve structures for acting on liquids having a difference in specific gravity. Such known valves act so that the float will control a valve depending upon the effective level of a heavier one of two liquids. However, such valves have not been applied for direct action in draining the settled water in storage tanks of petroleum products where settled water is gathered in a sump and connection to the sump is made by a dip leg conduit. Such conduit extends down into the sump from above. With such an arrangement the liquid in the sump must be drawn out through the dip leg conduit in order to remove the water or whatever liquid exists at the entrance of such conduit. Consequently, no direct connection of a float valve structure would be effective to carry out the separation of the heavier liquid, without some pumping to move the heavy liquid from the sump to such valve.
It was discovered that by employing a combination according to this invention, the circulation of liquid from a storage tank sump to a float controlled valve for draining the heavy liquid may be carried out with a minimal amount of energy exertion by making use of a closed system an employing a manual pump. Thus, the circulation of the liquid from the sump to a float valve may involve a very small amount of energy easily handled by a manual pump since the closed system for circulating the liquid is at substantially no difference in pressure.
Thus, it is an object of this invention, to provide a system that requires a minimum amount of equipment and saves operating personnel much time in carrying out a routine for removal or determination of whether any water is present in a storage tank of a hydrocarbon.